Days before Apple is set to unveil its flagship iPhone 6, a labor rights group revealed "a number" of human rights violations at a supplier factory used to build iPhone and iPad parts.

China Labor Watch and Green America on Thursday said a factory owned by Catcher Technology Co. in Suqian, China, was found to have "serious health and safety, environmental, and human rights violations." The facility manufactures metal iPad covers and other parts for the fifth-generation iPhones, China Labor Watch said. It noted that during its investigation in August, 5oo to 600 workers from Catcher Suqian were transferred to the factory's sister location in Taizhou to work on the upcoming iPhone 6.

"The investigation of Catcher Technology raises serious concerns around working conditions in Apple's second-tier supplier factories," Todd Larsen, corporate responsibility director for Green America, said in a statement. "We knew that we needed to make this information public to encourage Apple to take immediate next steps in addressing toxins and unsafe working conditions in their factories as Apple continues to ramp up production of the iPhone 6."

Apple, meanwhile, said it's "committed to ensuring safe and fair working conditions for everyone in our supply chain" and that it makes "it a priority to investigate every specific concern brought to our attention."

The condition of workers in the electronics industry has come under intense focus in recent months. Apple, Samsung, and many other large tech companies have faced fire over the treatment of the people building their phones, tablets, and other gadgets. As a result, the companies have pledged to do more to prevent the abuses. Apple even has said it plans to make more of its products in the US.

China Labor Watch, which was founded in 2000 and has since conducted a number of investigations in to Chinese factories, said that it investigated the same Suqian factory in April 2013 and found many of the same violations. At the time, the group reported its findings to Apple privately. Apple conducted its own investigation, the group said, and vowed to fix the problems, especially those related to worker safety.

"However, the results of CLW's subsequent undercover investigation of Catcher ... suggests that Apple and Catcher have done little to ensure that safety standards and other conditions have improved for Catcher's workers," China Labor Watch said. "In fact, the investigator going into the factory in 2014 discovered numerous additional violations that weren't found in 2013, as well as repeat violations from year to year, suggesting that conditions may actually be getting worse in the factory."

The issues found in Suqian in August included locked safety exits, a lack of safety training, hiring discrimination, excessive hours for workers, and forced overtime. China Labor Watch estimates each employee works six hours of unpaid overtime per month, resulting in roughly $290,000 in owed wages for all workers.

The group also found "significant" amounts of aluminum-magnesium alloy shreddings on the floor and dust particles in the air -- which pose a health and fire safety risk. And China Labor Watch said the factory dumps industrial fluids and waste into groundwater and nearby rivers. Employees also don't have proper equipment for handling toxic materials, the group said.

"CLW's investigation exposed more than 20 legal and ethical violations at the Catcher factory," Kevin Slaten, program coordinator at China Labor Watch, said in a statement. "This is exploitation by the factory and Apple for the sake of profit maximization."

Apple, meanwhile, acknowledged that Catcher's Suqian facility makes aluminum enclosures for MacBooks and iPads and said Apple's inspectors are there "constantly."

"We audit the facility's aluminum wet-polishing systems every month and consistently find that they exceed international safety standards," Apple said. "As a result of our quarterly fire-safety inspections, the most recent of which happened last week, Catcher has made same-day repairs of broken and expired fire extinguishers, unblocked corridors and fire exits, and added missing emergency exit signs."

Apple noted that its inspectors have found some areas for improvement and are working with Catcher "to develop a corrective action plan." They had scheduled a follow-up visit for next month but sent inspectors to the factory immediately after receiving China Labor Watch's report.

"Our suppliers must live up to the toughest standards in the industry if they want to keep doing business with Apple," the company said.

Apple is committed to ensuring safe and fair working conditions for everyone in our supply chain. We are the only technology company to be admitted to the Fair Labor Association, and our suppliers must live up to the toughest standards in the industry if they want to keep doing business with Apple.

We know our work is never done, and we are devoted to constant improvement. Last year we conducted 451 audits deep into our supply chain so we could uncover problems and work with our suppliers to fix them, and we make it a priority to investigate every specific concern brought to our attention.

Catcher Technology's Suqian facility makes aluminum enclosures for MacBook and iPad, and our inspectors are there constantly. We audit the facility's aluminum wet-polishing systems every month and consistently find that they exceed international safety standards. As a result of our quarterly fire-safety inspections, the most recent of which happened last week, Catcher has made same-day repairs of broken and expired fire extinguishers, unblocked corridors and fire exits, and added missing emergency exit signs.

Our most recent annual audit, in May, found some concrete areas for improvement in Catcher's operations, and we worked with Catcher to develop a corrective action plan. We had scheduled a follow-up visit next month to review their progress but have dispatched a team there immediately to investigate this report.

Excessive overtime is not in anyone's best interest, and we work closely with our suppliers to prevent it. We track and report the weekly working hours for more than 1 million workers, and, through the end of August, Catcher has averaged 95 percent compliance with our 60-hour workweek limit this year.

Catcher is among the 160 suppliers enrolled in our 18-month Apple Supplier EHS Academy training program, which we launched last year to raise the bar for environment, health and safety management in the industry.

About the author

Shara Tibken is a senior writer for CNET focused on Samsung and Apple. She previously wrote for Dow Jones Newswires and the Wall Street Journal. She's a native Midwesterner who still prefers "pop" over "soda."
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